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ACPI / EC: Add PM operations for suspend/resume noirq stage 

It is reported that on some platforms, resume speed is not fast. The cause
is: in noirq stage, EC driver is working in polling mode, and each state
machine advancement requires a context switch.

The context switch is not necessary to the EC driver's polling mode. This
patch implements PM hooks to automatically switch the driver to/from the
busy polling mode to eliminate the overhead caused by the context switch.

This finally contributes to the tuning result: acpi_pm_finish() execution
time is improved from 192ms to 6ms.

Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Reported-and-tested-by: Todd E Brandt <todd.e.brandt@linux.intel.com>
[ rjw: Subject ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Lv Zheng 2016-08-03 09:07:58 +08:00 committed by Rafael J. Wysocki
parent 694d0d0bb2
commit df45db6177
2 changed files with 55 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

53
drivers/acpi/ec.c
View File

@ -1619,6 +1619,58 @@ error:
return ret;
}
#ifdef CONFIG_PM_SLEEP
static void acpi_ec_enter_noirq(struct acpi_ec *ec)
{
unsigned long flags;
if (ec == first_ec) {
spin_lock_irqsave(&ec->lock, flags);
ec->saved_busy_polling = ec_busy_polling;
ec->saved_polling_guard = ec_polling_guard;
ec_busy_polling = true;
ec_polling_guard = 0;
ec_log_drv("interrupt blocked");
spin_unlock_irqrestore(&ec->lock, flags);
}
}
static void acpi_ec_leave_noirq(struct acpi_ec *ec)
{
unsigned long flags;
if (ec == first_ec) {
spin_lock_irqsave(&ec->lock, flags);
ec_busy_polling = ec->saved_busy_polling;
ec_polling_guard = ec->saved_polling_guard;
ec_log_drv("interrupt unblocked");
spin_unlock_irqrestore(&ec->lock, flags);
}
}
static int acpi_ec_suspend_noirq(struct device *dev)
{
struct acpi_ec *ec =
acpi_driver_data(to_acpi_device(dev));
acpi_ec_enter_noirq(ec);
return 0;
}
static int acpi_ec_resume_noirq(struct device *dev)
{
struct acpi_ec *ec =
acpi_driver_data(to_acpi_device(dev));
acpi_ec_leave_noirq(ec);
return 0;
}
#endif
static const struct dev_pm_ops acpi_ec_pm = {
SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(acpi_ec_suspend_noirq, acpi_ec_resume_noirq)
};
static int param_set_event_clearing(const char *val, struct kernel_param *kp)
{
int result = 0;
@ -1664,6 +1716,7 @@ static struct acpi_driver acpi_ec_driver = {
.add = acpi_ec_add,
.remove = acpi_ec_remove,
},
.drv.pm = &acpi_ec_pm,
};
static inline int acpi_ec_query_init(void)

2
drivers/acpi/internal.h
View File

@ -174,6 +174,8 @@ struct acpi_ec {
struct work_struct work;
unsigned long timestamp;
unsigned long nr_pending_queries;
bool saved_busy_polling;
unsigned int saved_polling_guard;
};
extern struct acpi_ec *first_ec;